Book-ends are those funny things that hold books upright on the shelf. They frame a series of books and keep them from falling over. When the books of the Bible are ordered based on Isaiah, book-ends appear around the Bible, the Testaments and the Gospels.
At the edges of the Bible the book order is unaffected by Isaiah. Genesis still opens the Bible and Revelation is the close. However, there is a book-end that confirms these books are correctly placed.
Revelation ends with a couple references to the "Tree of Life."
66 Revelation 22:2
2In the midst of the street of it, and on either side of the river, was there the tree of life, which bare twelve manner of fruits, and yielded her fruit every month: and the leaves of the tree were for the healing of the nations.
The Tree of Life first appears in the Garden of Eden, early in the book of Genesis.
1 Genesis 2:9
9And out of the ground made the Lord God to grow every tree that is pleasant to the sight, and good for food; the tree of life also in the midst of the garden, and the tree of knowledge of good and evil.
The beauty of these references to the Tree of Life is their proximity. Revelation only appears far from Genesis until you realize the context at the end of Revelation continues at the start of Genesis.
Connecting the end of Revelation to the book of Genesis we realize the New Jerusalem is just another name for the Garden of Eden. Both places contain the Tree of Life and there's no story in the Bible about transplanting that tree. In the Genesis account we learn about our past fall from Eden and Revelation predicts our future restoration to Eden.
Like the Bible the Old and New Testaments are framed with book-ends. Genesis and Daniel bracket the Old Testament. John and Revelation bracket the New Testament.
The Old Testament begins with the famous "In the beginning" verse.
1 Genesis 1:1
1In the beginning God created the heaven and the earth.
Daniel ends the Old Testament with a less famous but equally interesting reference to "The End."
39 Daniel 12:13
13But go thou thy way till the end be: for thou shalt rest, and stand in thy lot at the end of the days.
The Old Testament is thus bracketed with the simple ideas of "beginning" and "end."
The New Testament is bracketed the same way as the Old. You are probably familiar with how the Gospel of John begins. It's an echo of Genesis 1:1.
40 John 1:1-3
1In the beginning was the Word, and the Word was with God, and the Word was God.
2The same was in the beginning with God.
3All things were made by him; and without him was not any thing made that was made.
And Revelation, like Daniel, ends with "the end."
66 Revelation 22:13
13I am Alpha and Omega, the beginning and the end, the first and the last.
Revelation actually has more to say than just "the end." You may have noticed it mentions "the beginning" also. Why? It seems to be highlighting the high-level structure of the Bible. It has at least three words related to "beginning" and three related to "end." We haven't looked at the Gospel Book-ends yet, but Revelation appears to be summing up all three sections, the Bible, Testaments, and Gospels, by mentioning three beginnings and three ends.
The order of the Gospels is John, Matthew, Mark and Luke. Placing John as the first book in the Gospel series makes plenty of sense. It's noteworthy how often people are advised to begin their Bible reading with the Gospel of John. Yet even the opening line of the book attests to the idea that John comes first. John begins in the beginning.
40 John 1:1
1In the beginning was the Word, and the Word was with God, and the Word was God.
When John is placed first in the Gospel series a type of book-ends form between the end of John and beginning of Luke. Look at this statement near the end of John with the thought that you are reading the books in order and Matthew, Mark and Luke come next.
40 John 20:30
30¶And many other signs truly did Jesus in the presence of his disciples, which are not written in this book:
This statement refers to the things Jesus did in Matthew, Mark and Luke that are not recorded in John. It's consistent that a statement at the end of John would both separate John from the synoptic Gospels and prepare the reader to learn new things about Jesus in the following books.
Presumably we then read through Matthew and Mark before arriving at Luke. Luke then begins with a cryptic statement that references the preceeding Gospels. I'll quote the whole statement and then give some explanation verse by verse.
43 Luke 1:1-4
1Forasmuch as many have taken in hand to set forth in order a declaration of those things which are most surely believed among us,
2Even as they delivered them unto us, which from the beginning were eyewitnesses, and ministers of the word;
3It seemed good to me also, having had perfect understanding of all things from the very first, to write unto thee in order, most excellent Theophilus,
4That thou mightest know the certainty of those things, wherein thou hast been instructed.
The "works" which we (the readers) are familiar are everything we've read in John, Matthew and Mark before getting to Luke.
The phrases "the beginning" and "the Word" in this verse harken back to the start of John. Remember, "In the beginning was the Word (John 1:1)." Those who knew Jesus "handed down their observations" in the forms of John, Matthew and Mark. (We're not necessarily establishing the historical development of the Gospels here, that's a separate question, but we are asserting their canonical reading order.)
Luke cares about "order" so the idea that Luke would reveal his position in the book order before beginning his "orderly" account is consistent. In essence I read this whole opening statement as Luke saying, You're familiar with Jesus because of the stuff that's been passed down starting with John. I want to add just one more account, an orderly one.
Verse 4 reveals that Luke is addressed to Theophilus. One benefit of moving John to the start of the Gospel series is Luke returns to his natural place next to Acts, which is also addressed to Theophilus.
44 Acts 1:1-4
1The former treatise have I made, O Theophilus, of all that Jesus began both to do and teach,
2Until the day in which he was taken up, after that he through the Holy Ghost had given commandments unto the apostles whom he had chosen:
3To whom also he shewed himself alive after his passion by many infallible proofs, being seen of them forty days, and speaking of the things pertaining to the kingdom of God:
4And, being assembled together with them, commanded them that they should not depart from Jerusalem, but wait for the promise of the Father, which, saith he, ye have heard of me.
Each of the sections created by the book-ends is a series of related writings. The Bible is different from all other writings in the world. The Hebrew scriptures are distinguished from the Aramaic scriptures, though they work together wonderfully. The Gospels are also unique among the books of the Bible.